In general, a brake fluid reservoir is configured to hold brake fluid, which may change with respect to fluid level, fluid volume (e.g., fluid expansion or fluid contraction), fluid temperature, or any combination thereof. When experiencing at least one of these changes to the brake fluid, the brake fluid reservoir may experience a change in pressure. For example, when the fluid level of brake fluid within the brake fluid reservoir increases (e.g., during fluid return in accordance with an operation of an anti-lock braking system (ABS) or an electronic stability program (ESP)), the brake fluid reservoir tends to experience an increase in pressure. Alternatively, when the fluid level of brake fluid within the brake fluid reservoir decreases, the brake fluid reservoir tends to experience a decrease in pressure. In this regard, the brake fluid reservoir includes a ventilation system for pressure balancing.
However, the ability to retain brake fluid within the brake fluid reservoir and the ability to provide ventilation are often at odds with each other. For example, under various conditions, such as during anti-lock braking, acceleration, deceleration, or the like, there is a tendency for brake fluid, when held within the brake fluid reservoir, to come into direct contact with the ventilation system that is intended for pressure regulation. For instance, if the fluid volume of brake fluid is increased in accordance with an operation of the ABS and/or the ESP, then this fluid volume increase may result in brake fluid being ejected or discharged from the brake fluid reservoir.